I wrote this comment on the New Yorker website, but it seems relevant here:
I dont think US policymakers have (even now) a sufficient notion of what the problem is, a solution therefore seems unlikely.
In a different world, the US would admit it is in over its head and would pull out very quickly and let the locals and various regional powers fight it out. it will be extremely nasty in the region, but at least the US will not be directly involved...
Since it is actually unlikely that the US is ready to just pull out and leave the entire region to its own devices (what kind of worldcop would do that?), the most likely thing is that we will see more of the same. GHQ understands the US better than the US understands GHQ
Unless some miracle has happened, it is the US that is likely to find itself being frustrated and blundering from friend to enemy to friend with no good plan either way Making loud noises (the current accusations would normally constitute an act of war) while searching for a way to get out without humiliation. Pakistan will hurt even more, but the elite will find new sources of cash (China? Saudi Arabia?...not as generous and careless with money as Uncle Sam, but good enough for bad times) and will not suffer too much (poor people will suffer horribly, but who cares about them?). Eventually, the elite will also go down (or escape to the big bad United States), probably complaining about Zionist-Hindu-American plots until someone pries the microphone from their cold dead hands..but it will be an unpleasant mess and a long drawn out death, not a clean and clear "endgame". Too pessimistic?

Levi, I think the main casualties of an early US withdrawal will be US self-esteem and Pakistan's well being. India can get pulled in, but if they are really smart about it (OK, thats not the most likely course they will take) then they can survive with relatively little damage. There is no way Pakistan can make it out safely once the US leaves.